GTL500 Los Angeles

Please say HELLO and tell us about yourself, your bike[s] and where you are located etc...
Post Reply
motowrench
Cucciolo - the Lil Pup
Posts: 4
Joined: Tue Sep 04, 2018 12:27 pm

GTL500 Los Angeles

Post by motowrench » Tue Sep 04, 2018 2:32 pm

Hay all!

I kind of fell into a GTL500 (I know I should throw it away and set it of fire and punch myself in the face) It was a friend of mines fiance's who passed away and after years of him being frustrated with it, it was depressing him to have it around. I had always told him if he was ready to part with it i'd like to buy it because I have always liked unloved machinery and this bike is nowhere near the dumbest thing I have spent my money on.

So my plain is to fix the issues with it and make it a reasonably reliable bike keep it for a year and if I have fixed the issues with it offer to sell it back to him for what I bought it from him for $2000

Image

I did the Scottland green paint work and had the seat recovered.

Wish me luck.

motowrench
Cucciolo - the Lil Pup
Posts: 4
Joined: Tue Sep 04, 2018 12:27 pm

Re: GTL500 Los Angeles

Post by motowrench » Tue Sep 04, 2018 3:00 pm

I pulled the motor and took the topend off
Image

There are some scary things in here like this rocker that is not only drilled off center but also not perpendicular to the surface.
Image

An oil bypass seal that has a tear in it
Image

A fairly Micky mouse cam chain tenshioner
Image

A head mating surface that looks like it was machined with a belt sander
Image

But other wise the head and bores look ok
Image
Image

The rods/crank feel good the bike was running when I pulled it apart and didn't make any nasty noses.
The cam oil plugs where still in place
Oil was pumping up to the cams after 2 or 3 kicks.

This is my plain
#1 Make a more sensible wiring harness with dutch connectors and put in modern switches.
#2 Put in a 3 phase stator and reg/rec for real charging and use of lights
#3 Resurface all mating surfaces to prevent leaks
#4 Do the cam oil fix
#5 Go over the whole oil system and test the psi and different points
#6 A bunch of other stuff
#7 Build a second motor from the crank up in case this one fails.

User avatar
Gardner
Cucciolo - the Lil Pup
Posts: 13
Joined: Thu Jul 17, 2008 5:09 am
Location: Davenport, Ia

Re: GTL500 Los Angeles

Post by Gardner » Tue Sep 04, 2018 7:08 pm

Welcome motowrench, you're not crazy, you just like a challenge! I think you're going to have a cool Ducati that you don't see too often.
Sounds like you've already done more research and engineering than Ducati did when they designed it!
1978 SD Darmah
1979 SSD Darmah
1981 900SS
2017 Desert Sled
1982 Bimota HB2

ducadini
750 Sport [BEVEL]
Posts: 220
Joined: Sat Jul 31, 2004 8:54 am
Location: Antwerpen

Re: GTL500 Los Angeles

Post by ducadini » Tue Sep 04, 2018 10:07 pm

I guess You're Lucky : seems likt it is the second generation engine with the flat head. Previous the cylinders stuck out and fitted into the head (like the singles and v-twins) and were very hard to get gastight.
Some suggestions for the saving of the engine :
#1 Make a more sensible wiring harness with dutch connectors and put in modern switches. THAT is a very good idea, but compromises originality
#2 Put in a 3 phase stator and reg/rec for real charging and use of lights. The Original Motoplat should do just fine, the wiring is just "off"
#3 Resurface all mating surfaces to prevent leaks. Only leakage we had was the headgasket, others were all fine
#4 Do the cam oil fix. Together with the headgasket the most important fix, surf around a bit and find good solutions.
#5 Go over the whole oil system and test the psi and different points
#6 A bunch of other stuff
#7 Build a second motor from the crank up in case this one fails. Why not build ONE that performs well AND is reliable ?Or find Yourself a Desmo :-D :-D

ciao
ducadini
Nego i ricordi peggiori
Richiamo i migliori pensieri

motowrench
Cucciolo - the Lil Pup
Posts: 4
Joined: Tue Sep 04, 2018 12:27 pm

Re: GTL500 Los Angeles

Post by motowrench » Wed Sep 05, 2018 6:09 am

Thanks for the warm welcome guys. I haven't been on a forum in years becuase most of them are better at abusing you rather than teaching you anything. This one seems better.

Anyhow this is a fairly rare bike and I couldn't find a whole lot of images of one being restored so I thought for the sake of anyone else who might have one of these I'd show my work and any info I could find.

My head gasket and rocker covers do leak so I decked the head on my Vintage Italian milling machine. Who knows but some of these might have been in bologna factory.
Image
Image

The rocker covers I surfaced on a plate before I thought to take any photos but they where a bit taco shaped almost 1-MM out of flat at both ends

"THAT is a very good idea, but compromises originality"
I'm OK with compromising the originality, I'm not going to do anything that can't be bolted back on. Do you guys think I should cut the sub frame and make it a mono shock ;)

"The Original Motoplat should do just fine, the wiring is just "off""
Yeah I think the Diode filled indicator handle bar clamp thing is an analog nightmare and I think that thing has got to be making problems.
I'm sure the motoplat unit is probaly OK but I'd like to have new winddings keeping the battery topped up this bike has been a battery killer.
I've done some checking around and I think a KTM390 stator should work with and adapter plate. I'll wait until one pops up and I'll give it a try.
Why not build ONE that performs well AND is reliable ?Or find Yourself a Desmo :-D :-D
I will do some stuff to the back up motor. As over square as it is I would think it should make a lot more power. The head porting is better than Japanese bikes of the same era. The cam looks tame not a whole lot of valve overlap. The crank is stupid heavy but looks forged so I think you could remove 20% of it at the outer parts of the webs and balance it and get the thing to spin up faster. I've heard there where crank failures but I find that hard to beleave when you hold one in your hands. The whole motor feels over built but poorly executed. I think the best power gains to be had are by bumping the compression a bit and cc-ing the head if I was truly crazy I would have a billet cam ground for it :idea: :shock:

The good news is parts are out there and fairly cheep.

motowrench
Cucciolo - the Lil Pup
Posts: 4
Joined: Tue Sep 04, 2018 12:27 pm

Re: GTL500 Los Angeles

Post by motowrench » Wed Sep 05, 2018 8:19 am

Image

Looks like I spoke to soon about the bores being good when I was cleaning them up a big depression showed up right where the cylinder casting ends on the sleeve and the oil rings land at BDC. I grabbed a set of sleeves off ebay but I'd rather find some pistons being that this is the original bore.

Vince
750 GT
Posts: 193
Joined: Tue Nov 09, 2004 12:28 am

Re: GTL500 Los Angeles

Post by Vince » Thu Sep 06, 2018 4:55 pm

One of these was built into one crazy fast race bike in Oz back in the 80s by one of the local Sydney Ducati Guros.Epicycles
https://netrider.net.au/threads/ducati- ... ns.233839/

Post Reply

Return to “Introduce Yourself”